People with diabetes who engaged in basic physical activity after eating had blood sugar levels close to those of people without the condition, the study showed. Those who remained sedentary after meals had elevated blood sugar levels.

"You don't have to exercise a lot. Just walking the dog or washing the dishes after a meal, rather than going straight from the table to the TV, helps blood sugar control in people with type 1 diabetes," Kudva tells WebMD. "Physical activity enhances insulin action, hence lowering blood glucose concentration."

Exercise and Diabetes

About 3 million Americans have type 1 diabetes, which is usually diagnosed in childhood or young adulthood. It's an autoimmune disease in which the body destroys its own ability to make insulin, which is needed to properly regulate blood sugar.

For the study, the researchers monitored 14 people without diabetes and seven people with type 1 diabetes over a four-day period at the Mayo Clinic in Rochester, Minn.

Participants were given three identical meals each day. After one meal each day, participants laid in bed for six hours. After the other meals, they engaged in physical activity. Overall, participants walked at a moderate pace for an average of 3 to 4 miles a day, "about the same as the average American," Kudva says.

The sugars in one meal a day were labeled with a safe tracing dye so the researchers could measure how much sugar from food went in and how much came out.

The findings were presented here at the annual meeting of the American Diabetes Association.

Checking Blood Sugar Levels

Among people without diabetes, post-meal blood glucose levels increased an average of 50 milligrams per deciliter (mg/dL) if they exercised after eating. That is what we like to see in healthy people," Kudva says. Readings increased by up to 100 mg/dL if they were inactive.

Among people with type 1 diabetes, blood glucose levels rose an average of 80 milligrams per deciliter if they exercised after eating and 150 mg/dL if they were inactive.

Most people without diabetes have blood sugar levels in the 70s, while people with the condition aim for a reading of 70-130 mg/dL. The recommended post-meal blood sugar level for people with diabetes is less than 180 mg/dL.

"If a diabetic patient's blood sugar is 100 or higher before eating, an increase of 150 is pretty significant," Kudva says. Over time, persistently high blood sugar can give rise to a host of complications ranging from blindness to kidney problems, he says.

James B. Meigs, MD, of Harvard Medical School, tells WebMD that there's been a lot of debate about the right amount of exercise for people with diabetes.

"This confirms that a little exercise is better than none. It's the people who are really sedentary who have poor blood sugar control," he says.

These findings were presented at a medical conference. They should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.